Immutables allows you to embrace immutablity to tackle complexity and concurrency challenges. To get the benefits of immutability in Java, there's an annotation processor to easily create simple and consistent value objects. You can think of it as Guava's Immutable Collections but for regular objects. It includes support for JSON marshaling, MongoDB repositories, and JAX-RS.

WebAnno is a general purpose Web-based annotation tool for a wide range of linguistic annotations. It offers annotation project management, freely configurable tagsets, and the management of users in different roles. It uses technology from the brat rapid annotation tool for visualizing and editing annotations in a Web browser. It supports annotation and visualization of arbitrarily large documents, pluggable import/export filters, the curation of annotations across various users, and farming out annotations to a crowdsourcing platform.

Corn CPS (Classpath Scanner) is a small Java module to help you to find classes and files in your classpath. The scanner is able to scan jar files, classpath directories, and Web application directories.

CarrotGarden SCR provides an OSGI Service-Component descriptor generator according to a proposal described in RFC 0172 Declarative Services Annotations. It is
comprised of annotations, a Maven plugin, and an Eclipse connector, and allows for interactive SCR component descriptor updates in Eclipse, which are compatible with non-interactive Jenkins Maven builds.

AnoForPHP is an experimental patch to PHP/ZendEngine to bring native annotations to PHP. It lets you annotate classes, methods, and arguments for the methods. The annotation token is "@@", because "@" was already taken.

Gromit-MPX is a multi-pointer GTK3 port of the original Gromit desktop annotation tool. It enables graphical annotations with several pointers at once and is a lot faster than its predecessor since it uses the XCOMPOSITE extension where available.